Anton Shemerey@shemerey

Single Responsibility Principle в Руби или почему instance/class variables это ОЧЕНЬ плохо

each object should have one and

only one responsibility

Dear Anton Shemerey.

Thank you for your patronage. This letter is to confirm that your order fromDoe Books has been filled and should arrive within 15 days.

Shipping books at the book rate generally slows delivery. As you know, paymentin full ($20.75) is due by the end of the month.

Thank you for doing business with Doe. We look forward to serving you again.If you have questions regarding the new pricing please contact support.

--

Sincerely yours, John PeterDoe Books

720 S Michigan AveChicago, IL, United States+1 312-922-4400

Order Confirmation Page

Dear. Anton Shemerey

Thank you for your patronage. This letter is to confirm that your order fromDoe Books has been filled and should arrive within 15 days.

Shipping books at the book rate generally slows delivery. As you know, paymentin full ($20.75) is due by the end of the month.

Thank you for doing business with Doe Books. We look forward to serving you again.If you have questions regarding the new pricing please contact support.

--

Sincerely yours, John PeterDoe Books

720 S Michigan AveChicago, IL, United States+1 312-922-4400

Order Confirmation Page variables

Dear. {%user_full_name%}

Thank you for your patronage. This letter is to confirm that your order from{%company_name%} has been filled and should arrive within {%delivery_time%}.

Shipping books at the book rate generally slows delivery. As you know, paymentin full ({%order_total%}) is due by the end of the month.

Thank you for doing business with {%company_name%}. We look forward to serving you again. If you have questions regarding the {%price_url%} please contact {%support_email%}.

--

Sincerely yours, {%owner_name%}{%company_name%}

{%company_address%}

Order Confirmation Template

Data we have :(

• current_user.full_name #=> ‘Anton Shemerey’

• @order.estimated_delivery #=> ’15 days’

• @order.total #=> ‘<Money: @cents = 2075 ….’

• COMPANY_NAME #=> ‘Doe Books’

• $owner.full_name #=> ‘John Peter’

• @pricing_link #=> ‘http://example.com/price'

• $support_email = ‘support@example.com’

• @@company_address #=> ‘720 S Michigan Ave Chicago….’

Facepalm

Dear. <%= current_user.full_name %>

Thank you for your patronage. This letter is to confirm that your order from<%= COMPANY_NAME %> has been filled and should arrive within <%= @order.estimated_delivery%>.

Shipping books at the book rate generally slows delivery. As you know, paymentin full (<%= number_to_currency(@order.total) %>) is due by the end of the month.

Thank you for doing business with <%= COMPANY_NAME %>. We look forward to serving you again. If you have questions regarding the <%= @pricing_link %> please contact <%= email_to(“Support”, $support_email) %>.

--

Sincerely yours, <%= $owner.full_name %><%= COMPANY_NAME %>

<%= @@company_address %>

Order Confirmation Template

THE Controller :)

class OrdersController < ApplicationController .... def confirmation @order = Order.find(params[:id]) end ....end

Dear. <%= current_user.full_name %>

Thank you for your patronage. This letter is to confirm that your order from<%= COMPANY_NAME %> has been filled and should arrive within <%= @order.estimated_delivery%>.

Shipping books at the book rate generally slows delivery. As you know, paymentin full (<%= number_to_currency(@order.total) %>) is due by the end of the month.

Thank you for doing business with <%= COMPANY_NAME %>. We look forward to serving you again. If you have questions regarding the <%= @pricing_link %> please contact <%= email_to(“Support”, $support_email) %>.

--

Sincerely yours, <%= $owner.full_name %><%= COMPANY_NAME %>

<%= @@company_address %>

Order Confirmation Template

Dear. <%= @current_user_full_name %>

Thank you for your patronage. This letter is to confirm that your order from<%= @company_name %> has been filled and should arrive within <%= @estimated_delivery_time %>.

Shipping books at the book rate generally slows delivery. As you know, paymentin full (<%= number_to_currency(@order_total) %>) is due by the end of the month.

Thank you for doing business with <%= @company_name %>. We look forward to serving you again. If you have questions regarding the <%= link_to(‘price’, @pricing_link) %> please contact <%= email_to(“Support”, @support_email) %>.

--

Sincerely yours, <%= @owner_full_name %><%= @company_name %>

<%= @company_address %>

Order Confirmation Template Second Attempt

THE Controller :)class OrdersController < ApplicationController .... def confirmation @order = Order.find(params[:id]) @current_user_full_name = current_user.full_name @company_name = COMPANY_NAME @estimated_delivery_time = @order.estimated_delivery @order_total = @order.total @pricing_link = 'http://example.com/price' @support_email = 'support@example.com' @owner_full_name = $owner.full_name @company_address = @@company_address end ....end

Second Attempt

Dear. Anton Shemerey

Thank you for your patronage. This letter is to confirm that your order fromDoe Books has been filled and should arrive within 15 days.

Shipping books at the book rate generally slows delivery. As you know, paymentin full ($0) is due by the end of the month.

Thank you for doing business with Doe Books. We look forward to serving you again. If you have questions regarding the new pricing please contact support.

--

Sincerely yours, John PeterDoe Books

720 S Michigan AveChicago, IL, United States+1 312-922-4400

Free Order !!!!

Five sec to fix ;-)

class OrdersController < ApplicationController # .... def confirmation @order = Order.find(params[:id]) @current_user_full_name = current_user.full_name @company_name = COMPANY_NAME @estimated_delivery_time = @order.estimated_delivery @order_total = @order.total

@pricing_link = 'http://example.com/price' @support_email = 'support@example.com' @owner_full_name = $owner.full_name @company_address = @@company_address end # ....end

binding.pry

require 'pry'; binding.pry

2.0.0-p353 :006 > @order_total => #<Money:0x007fc7afb23530 @cents=83991, @currency="USD", @bank=#<Money::VariableExchangeBank:0x007fc7a36415c8 @rates={}, @mutex=#<Mutex:0x007fc7a3641528>>>

WTF ?!?!?!?!

Dear. <%= @current_user_full_name %>

Thank you for your patronage. This letter is to confirm that your order from<%= @company_name %> has been filled and should arrive within <%= @estimated_delivery_time %>.

Shipping books at the book rate generally slows delivery. As you know, paymentin full (<%= number_to_currency(@order_total) %>) is due by the end of the month.

Thank you for doing business with <%= @company_name %>. We look forward to serving you again. If you have questions regarding the <%= link_to(‘price’, @pricing_link) %> please contact <%= email_to(“Support”, @support_email) %>.

--

Sincerely yours, <%= @owner_full_name %><%= @company_name %>

<%= @company_address %>

Order Confirmation Template binding.pry

<%- require 'pry'; binding.pry %>

2.0.0-p353 :0016 > @order_total => #<Money:0x007fc7afb23530 @cents=0, @currency="USD", @bank=#<Money::VariableExchangeBank:0x007fc7a36415c8 @rates={}, @mutex=#<Mutex:0x007fc7a3641528>>>

WTF ?!?!?!?!

GREP!!!

$ grep -iRn @order_total app | wc

#=> 151 1017 17348

How are rails instance variables passed to

views?????

AbstractController::Rendering#view_assigns

module AbstractController module Rendering # .... # This method should return a hash with assigns. # You can overwrite this configuration per controller. # :api: public def view_assigns protected_vars = _protected_ivars variables = instance_variables

variables.reject! { |s| protected_vars.include? s } variables.each_with_object({}) { |name, hash| hash[name.slice(1, name.length)] = instance_variable_get(name) } end # .... endend

module AbstractController def view_context view_context_class.new(

view_renderer, view_assigns, self) endend

AbstractController#view_context

GREP!!!$ grep -iRn @order_total app/helpers | wc

#=> 2 8 143

Second Attempt

module ApplicationHelper .... def current_cart_total if current_user if order = current_user.current_order @order_total = order.total end else @order_total = Money.new(0) end end ....end

$ git blame | grep current_cart_total

Problem Fixed!

class OrdersController < ApplicationController before_action :load_order, only: [:show, :update, :destroy]

def update if @order.update_attributes(params[:order]) redirect_to :show else render 'edit' end end

private

def load_order @order = Order.find(params[:id]) endend

Controller.before_action

class OrdersController < ApplicationController .... def order @order ||= Order.find(params[:id]) end ....end

Memoization

class OrdersController < ApplicationController helper_method :order

def update if order.update_attributes(params[:order]) redirect_to :show else render 'edit' end end

private

def order @_order ||= Order.find(params[:id]) endend

Controller.helper_method

• memoization / lazy loading

• encapsulating (getter, setter)

• barewords (method, local variable, helper_method, ….)

#source_location, caller

def total_order stack = caller require 'pry'; binding.pry ...end

<% self.method(:total_order).source_location %>

one action one @

• PRESENTER

• SERVICE OBJECT

• PROXY OBJECT

• VALUE OBJECT

• LOCALS

• HELPER_METHOD

You can always use following

#destroy_all_view_assigns

group :development, :test do gem 'destroy_all_view_assigns'end

https://github.com/shemerey/destroy_all_view_assigns

https://github.com/shemerey

https://www.facebook.com/shemerey

https://twitter.com/shemerey

https://www.linkedin.com/in/shemerey

Questions ???